return pump help
- Thread starter glxtrix
- Start date
How big is your sump, does it have a fuge and if so how big is it?
I wouldn't go above 600gph per 1" bulkhead as a max. You can do 800gph in some instances but I would not encourage it. Also, this is the max not necessarily the right amount.
I wouldn't go above 600gph per 1" bulkhead as a max. You can do 800gph in some instances but I would not encourage it. Also, this is the max not necessarily the right amount.
- Messages
- 140
- Reaction score
- 0
General rule of thumb is maintain at LEAST 2 foot per second (fps) flow in the pipe to keep any solids from settling in the pipe. For a 1" pipe this would be about 300 gph. You usually don't want to exceed 8 fps because you get a lot of friction/line losses in the pipe making the pump very inefficient. So you have a range of 300-1200 gph. I say go for the middle, between 600-800 gph.
All of these numbers are based on pipe diameter. If you use smaller (3/4") pipe, you will have to scale back.
Also remember to look at your pump curve to know your flow at the head you are pumping; i.e. your flow will be different if you are pumping 3' to your tank versus 6' to your tank. And make sure that when you figure how far you are pumping that you use the water elevation in the tank, not the pipe height.
For example:
Sump is on floor, pump is in sump. Sump water level is 12".
Tank stand is 30".
Drilled fitting on tank is 12" above stand.
Tank water level is 28" above stand.
On the pump curve you need to look at the flow corresponding to the difference between the two water levels, i.e.
Tank water level - sump water level=
(28"+30") - 12" = 46" = 3.8'
It does not matter where your hole is drilled in the tank or what level the pump is located. Then you still need to derate the pump for friction in the pipe, but that all depends on the flow through the pipe. The higher the fps, the more friction, the less the flow.
If you have multiple pipes it gets more confusing, but the best thing is to tee or branch off soon after the pump. Then you can calculate the flow in each pipe separately and add the flows together. Just make sure that your pump suction pipe is large enough to handle the flow (usually it is one size larger than the discharge pipe). I would also recommend adding ball valves to each line to the tank if you use just one pump. That way you can balance the flow manually after you start, plus you can perform maintenance on one segment while the tank is still running.
If the flow is closed loop, then you use the highest flow pump curve and only de-rate the curve for friction losses.
Are you running closed loop or sump?
All of these numbers are based on pipe diameter. If you use smaller (3/4") pipe, you will have to scale back.
Also remember to look at your pump curve to know your flow at the head you are pumping; i.e. your flow will be different if you are pumping 3' to your tank versus 6' to your tank. And make sure that when you figure how far you are pumping that you use the water elevation in the tank, not the pipe height.
For example:
Sump is on floor, pump is in sump. Sump water level is 12".
Tank stand is 30".
Drilled fitting on tank is 12" above stand.
Tank water level is 28" above stand.
On the pump curve you need to look at the flow corresponding to the difference between the two water levels, i.e.
Tank water level - sump water level=
(28"+30") - 12" = 46" = 3.8'
It does not matter where your hole is drilled in the tank or what level the pump is located. Then you still need to derate the pump for friction in the pipe, but that all depends on the flow through the pipe. The higher the fps, the more friction, the less the flow.
If you have multiple pipes it gets more confusing, but the best thing is to tee or branch off soon after the pump. Then you can calculate the flow in each pipe separately and add the flows together. Just make sure that your pump suction pipe is large enough to handle the flow (usually it is one size larger than the discharge pipe). I would also recommend adding ball valves to each line to the tank if you use just one pump. That way you can balance the flow manually after you start, plus you can perform maintenance on one segment while the tank is still running.
If the flow is closed loop, then you use the highest flow pump curve and only de-rate the curve for friction losses.
Are you running closed loop or sump?
- Messages
- 140
- Reaction score
- 0
Thiago,
You bring up a VERY good point. I did not consider the gravity line to the sump. I only focused on pump delivery rate and flow in the piping. It is very important to not pump more up to the tank than your drain piping will allow back to the sump unless you like a wet floor. In a closed loop it is a non factor since the pump will suck in as much as it pumps out (within reason - making sure that the suction line is larger than discharge line as above so you don't cavitate the pump). So the other question would be how large large are the gravity lines versus the pump return lines? The gravity drain lines could be the limiting factor.
You bring up a VERY good point. I did not consider the gravity line to the sump. I only focused on pump delivery rate and flow in the piping. It is very important to not pump more up to the tank than your drain piping will allow back to the sump unless you like a wet floor. In a closed loop it is a non factor since the pump will suck in as much as it pumps out (within reason - making sure that the suction line is larger than discharge line as above so you don't cavitate the pump). So the other question would be how large large are the gravity lines versus the pump return lines? The gravity drain lines could be the limiting factor.
- Messages
- 140
- Reaction score
- 0
Forgot to mention, for gravity piping you usually don't want to exceed 5 fps (750 gph in a 1" line) due to excessive friction and in our systems with air in the lines and other issues, I would not go more than 4 (600 gph). So Thiago's rule of thumb of 600 gph sounds good to me.
Chris
Chris
Lee, what size tank are you talking about and was it already drilled? Is a 1" overflow and 3/4" return a standard? I'm going to drill two tanks, a 30G hooked up to a 20G sump, and a 29G that will be a refugium as part of my 120G system. I'm still trying to figure out what size overflow and retun to drill for.
- Messages
- 140
- Reaction score
- 0
Based on your tank dimensions (140-gal tank) and sump dimensions (55-gal sump) I would use a mag 5. See the attached calculations and pump curve.
<fieldset class="gc-fieldset">
<legend> Attached files </legend>
<fieldset class="gc-fieldset">
<legend> Attached files </legend>
You want to shoot for 20-30x flow through a fuge and 5-10x flow through the sump. The drain line should not determine how much you should be pumping beyond limiting you to what you can do.
I am going to keep with my original statement that 600gph should be considered the max but in most instances you can hit 800gph without issue. If you try to push over 800gph with a gravity feed you will likely cause an overflow in the main tank onto the floor. 600-800gph works, but any slight alteration in the drain such as a medium sized snail will likely have you breaking out a mop as well. 600gph is the saftest max I know of.
I am going to keep with my original statement that 600gph should be considered the max but in most instances you can hit 800gph without issue. If you try to push over 800gph with a gravity feed you will likely cause an overflow in the main tank onto the floor. 600-800gph works, but any slight alteration in the drain such as a medium sized snail will likely have you breaking out a mop as well. 600gph is the saftest max I know of.
so that 600gph is after head loss correct? Cuz with my 55g now with 30g sump and fuge I have a MAG5 on it and its running great, not to mention pump is running full throttle. As far as sump question goes i plan on going true BB with this tank, meaning no fuge just a sump that contains water.
yeah i was thinking the same thing for the fuge, i always thought that supposed to be a slow area. Thanks Thiago I was thinkng of having it drain directly to the skimmer....guess we'll see what happens whenever I decide to do all this mess.
- Messages
- 4,441
- Reaction score
- 1,330
Wow Stanfillreef... + 1!
